This invention relates to a carrier matrix in particular for a catalytic reactor for the purification of the exhaust gas of internal combustion engines.
It is shown by German Patent DE-OS No. 29 02 779 to make a matrix of different foils for a catalytic reactor for purifying exhaust gas by rolling up the foils. Smooth metal foils and corrugated metal strips are alternately placed against one another and rolled up together. Subsequently, these metal foils are soldered. In a further work step, they are coated with a catalyst material. The corrugated strips between the smooth foils, in a matrix of this type, form passage ducts for the exhaust gas, which by means of slanting several corrugated strips arranged behind one another, the turbulence of the exhaust gases flowing through can be also increased in the area between two smooth foils.
It is shown in German Patent DE-PS No. 27 33 640 to make the smooth metal foils with stamped-out areas or projections which engage into openings in the corrugated foil, and hook together during the layering or rolling-up, so that relative sliding of the individual layers is avoided. As a result, under certain circumstances, a soldering process is unnecessary. It is a disadvantage of this arrangement that during the rolling-up or the layering, the layers that are to be applied on top of one another must be mutually aligned, making the manufacturing process costly. Also, it cannot be ensured in all cases that the individual layers in each matrix are placed on top of one another in the same way. The result may be that in different carrier matrices, catalyst surfaces exist that have a different effect on the exhaust gas, which is undesirable with respect to the utilization of the catalyst material.
A further disadvantage is that catalyst bodies made in this way, although causing an increase in turbulence within the individual flow-through ducts bordered by the flat metal foils, allow almost no gas compensation to take place in radial direction which, with respect to a utilization of the catalyst material, is also undesirable. It was suggested in German Patent DE-PS No. 33 47 086.3 to layer metal foils directly on top of one another, in the manner of turbulence plates as they are used in heat exchangers. However, such types of construction, with respect to manufacturing technology, have certain disadvantages.
An objective of the present invention is to avoid these disadvantages by creating a carrier matrix of the initially mentioned type which permits a good utilization of the catalyst materials combined with a simple manufacturing method.
This and other objectives are achieved by providing a carrier matrix with a flat foil and a corrugated foil, arranged as alternating layers. The corrugated foil has a plurality of corrugations, with each corrugation having a plurality of segments fluidly connected behind one another in air flow direction, and transversely staggered to each other with respect to the air flow direction.
The foils of the present invention can be placed on top of one another in a simple manner regardless of the shape of the corrugations or the profile of the corrugations. The foils are excellently suited for the making of wound carrier matrices because the continuous flat metal foil can absorb the tensile stress exercised during the rolling-up of the foils, while the corrugated segments, because of their continuous contacting arrangement with the flat strip over the entire width of the flat strip, also cannot be deformed during the winding process in an undesirable manner. This is because the corrugated metal segments of the present invention have a high inherent stability.
Despite the use of a continuous flat foil, a radial gas compensation in the carrier matrix body can be achieved in a relatively simple manner between the individual layers or windings by providing openings in the flat foil. In this manner, a connection can be established between the flow duct segments of foils disposed above one another. Also, the flow duct segments that laterally border on one another formed by the corrugations are connected with one another so that a good gas compensation is achieved during the flow-through. Finally, especially preferred embodiments provide corrugated segments which have corrugations with a trapezoidal cross-section which are arranged such that the smaller of the two parallel sides of the trapezoid forms the side that is closed by the corrugated strip, while the larger of the sides forms the open side of the corrugated strip. This trapezoidal cross-section results in a very good stability of the corrugated strip which is significant for the winding-up of the matrix.
Further objects, features and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings, which show for purposes of illustration only, an embodiment constructed in accordance with the present invention.